Regenerative thermal oxidiser

Abstract

A heat exchanger for a regenerative thermal oxidiser is described. The heat exchanger has a heat exchange bed that is disposed within a housing. The heat exchange bed is disposed parallel to the longest axis of the housing. A cavity is formed at either side of the heat exchange bed. Channels in the heat exchange bed link the two cavities. Because the heat exchange bed is disposed parallel to the longest axis of the housing, the area of the heat exchange bed facing the cavities is maximised, and the length of the channels is minimised, this reduces the pressure required to drive gas through the heat exchanger.

1 . A heat exchanger for a regenerative thermal oxidiser comprising
 a housing, having a plurality of walls, defining a chamber;   a heat exchange bed, disposed in said chamber in a plane parallel to the longest axis of said chamber, said heat exchange bed defining a first cavity and a second cavity within said chamber, said first cavity and said second cavity extending substantially the length of said longest axis of said chamber, said heat exchange bed having a plurality of channels between said first cavity and said second cavity.   
     
     
         2 . The heat exchanger of  claim 1 , further comprising a passive flow controller in at least one of the first cavity and the second cavity. 
     
     
         3 . The heat exchanger of  claim 2 , said housing having a first opening connecting to said first cavity and a second opening connecting to said second cavity, wherein said first and second openings are in walls of said plurality of walls that are perpendicular to said plane and wherein said first and second openings are in opposing walls of said plurality of walls. 
     
     
         4 . The heat exchanger of  claim 3 , wherein said passive flow controller comprises a protrusion adjacent to said second opening extending from an inner surface of said housing facing said heat exchange bed into said second cavity. 
     
     
         5 . The heat exchanger of  claim 4 , wherein said protrusion is substantially triangular in cross section. 
     
     
         6 . The heat exchanger of  claim 5 , wherein said protrusion extends substantially across the width of said second opening. 
     
     
         7 . The heat exchanger of  claim 2 , wherein said passive flow controller comprises a plurality of vanes located in said first cavity. 
     
     
         8 . The heat exchanger of  claim 7 , wherein said vanes extend outwardly from said heat exchange bed in the direction of said channels and bend towards said first opening in said first cavity. 
     
     
         9 . The heat exchanger of  claim 8 , wherein said vanes of said plurality of vanes extend further from said heat exchange bed in regions further from said first opening. 
     
     
         10 . The heat exchanger of  claim 1 , said housing comprising a shipping container. 
     
     
         11 . The heat exchanger of  claim 1 , said heat exchange bed being formed from a plurality of ceramic blocks said ceramic blocks each having a plurality of channels running therethrough. 
     
     
         12 . The heat exchanger of  claim 11 , wherein at least two of said channels of said plurality of channels running through said ceramic blocks are interconnected. 
     
     
         13 . The heat exchanger of  claim 3 , said heat exchange bed having a first region adjacent to said first opening, a second region adjacent to said second opening and a third region between said first and second regions, wherein said heat exchange bed is thicker in said first and/or second regions than in said third region. 
     
     
         14 . A valve assembly for a regenerative thermal oxidiser comprising:
 a housing, forming a valve chamber, said housing comprising
 an inlet duct opening; 
 an outlet duct opening; 
 a first heat exchange bed opening; and 
 a second heat exchange bed opening, 
   a valve blade, rotatable around an axis within said chamber   wherein said housing is provided with inwardly facing protrusions that limit the angular position of said valve blade between a first radial position and a second radial position, said protrusions being in contact with said valve blade when said valve blade is in said first or said second position and preventing fluid flow from said inlet duct opening to said outlet duct opening.   
     
     
         15 . The valve assembly of  claim 14  wherein said inlet duct opening is on an opposing face of said housing to said outlet duct opening. 
     
     
         16 . The valve assembly of  claim 14  wherein when said valve blade is in an angular position between said first and said second position fluid can flow from said inlet duct opening to said outlet duct opening. 
     
     
         17 . The valve assembly of  claim 14 , wherein the thickness of said valve blade does not substantially vary with radial distance from said axis. 
     
     
         18 . The valve assembly of  claim 14  further comprising a first heat exchange bed duct connected to said first heat exchange duct opening and a second heat exchange bed duct connected to said second heat exchange bed opening, wherein said first and second heat exchange bed ducts extend outwardly from said first axis and then bend such that first and second heat exchange bed ducts follow parallel paths perpendicular to said first axis 
     
     
         19 . The valve assembly of  claim 18 , further comprising an outlet duct connected to said outlet duct opening, said outlet duct running away from said first axis parallel to said parallel paths of said first and second heat exchange bed ducts and then turning to a direction parallel to said first axis. 
     
     
         20 . The valve assembly of  claim 19 , further comprising a vent located in a plane perpendicular to said first axis, wherein said outlet duct connects to said vent. 
     
     
         21 . The valve assembly of  claim 14 , wherein said outlet duct opening is formed in a surface of said housing perpendicular to said axis to allow fluid flow from said valve chamber parallel to said axis. 
     
     
         22 . A heat exchanger according to  claim 1  comprising a valve assembly according to  claim 14  integrated within said housing of said heat exchanger. 
     
     
         23 . A regenerative thermal oxidizer comprising
 a first heat exchanger comprising
 a housing, having a plurality of walls, defining a chamber; 
 a heat exchange bed, disposed in said chamber in a plane parallel to the longest axis of said chamber, said heat exchange bed defining a first cavity and a second cavity within said chamber, said first cavity and said second cavity extending substantially the length of said longest axis of said chamber, said heat exchange bed having a plurality of channels between said first cavity and said second cavity; 
   a second heat exchanger comprising
 a housing, having a plurality of walls, defining a chamber; 
 a heat exchange bed, disposed in said chamber in a plane parallel to the longest axis of said chamber, said heat exchange bed defining a first cavity and a second cavity within said chamber, said first cavity and said second cavity extending substantially the length of said longest axis of said chamber, said heat exchange bed having a plurality of channels between said first cavity and said second cavity; 
   an inlet;   an outlet;   a valve assembly operable to selectively connect said inlet to said first cavity of either of said first heat exchanger and said second heat exchanger and said outlet to the other; and   a combustion chamber connected between said second cavity of said first heat exchanger and said second cavity of said second heat exchanger.   
     
     
         24 . The regenerative thermal oxidiser of  claim 23 , wherein said first heat exchanger and said second heat exchanger further comprise a passive flow controller in at least one of the first cavity and the second cavity. 
     
     
         25 . The regenerative thermal oxidiser of  claim 23 , further comprising an active flow controller. 
     
     
         26 . The regenerative thermal oxidiser according to  claim 23 , said first heat exchanger being arranged on top of said second heat exchanger. 
     
     
         27 . The regenerative thermal oxidiser of  claim 23 , said valve assembly comprising:
 a housing, forming a valve chamber, said housing comprising
 an inlet duct opening; 
 an outlet duct opening; 
 a first heat exchange bed opening; and 
 a second heat exchange bed opening, 
   a valve blade, rotatable around an axis within said chamber   wherein said housing is provided with inwardly facing protrusions that limit the angular position of said valve blade between a first radial position and a second radial position, said protrusions being in contact with said valve blade when said valve blade is in said first or said second position and preventing fluid flow from said inlet duct opening to said outlet duct opening.   
     
     
         28 . The regenerative thermal oxidiser of  claim 23 , having a diesel fired heater in said combustion chamber. 
     
     
         29 . The regenerative thermal oxidiser of  claim 25 , said active flow controller comprising a fan connected to said inlet, wherein said fan has a variable speed drive. 
     
     
         30 . A method of manufacture of a heat exchanger for a regenerative thermal oxidiser, said method comprising
 providing a shipping container;   lining at least part of the interior of said shipping container with steel plate;   attaching insulation to at least part of said steel plate; and   arranging blocks of a heat exchange material within said shipping container.   
     
     
         31 . A method of manufacturing a regenerative thermal oxidiser, said method comprising:
 providing a first shipping container and a second shipping container;   lining at least part of the interior of said first shipping container and said second shipping container with steel plate;   attaching insulation to at least part of said steel plate in said first shipping container and said second shipping container;   placing said first shipping container on top of said second shipping container; and   arranging blocks of a heat exchange material within said first shipping container and said second shipping container.